i use Linux with freeglut3 (2.4.0-8). Every time i create a context an opengl 2.1 context is created. Is there any way to define which kind of context will be created?

Via glXCreateContextAttribsARB it's no problem to create the opengl 3.1 context but than i don't know how to use glut in combination with that 'manually' created context.

Greetings,

Jotschi

marshats

12-05-2009, 08:16 AM

As you know, GLUT itself has been frozen in time but it has a updated and extended opensource replacement freeglut (http://freeglut.sourceforge.net/). I have been using the latest SVN recently which contains the ability to create an ogl3 context. However, there is a new stable release that I haven't tried yet "Freeglut 2.6.0 [Released: 27 November 2009]" that you could update to and try. -- I will try it too when I get a chance since it would be nice to be using a stable branch instead of testing their SVN unstable branch all the time.

There is an example in the 2.6.0 release which shows how to get a 3.1 context ... freeglut-2.6.0/progs/demos/smooth_opengl3/ pay particular attention to the following header line and two lines in the smooth_opengl3.c

I consider this a temporary solution that will be cleaner when ubuntu catches up to the 2.6 release!

Note, I use gl3.h (http://www.opengl.org/registry/api/gl3.h) from openGL registry (http://www.opengl.org/registry/) to replace the initExtensionEntries() and other related crust -- freglut did it that way to avoid having extra libraries in their source examples. And that example code consequently mangles glFunction names as gl_function name -- I don't like this so here is my more "standard" code if you like

/*
* smooth_opengl3.c, based on smooth.c, which is (c) by SGI, see below.
* This program demonstrates smooth shading in a way which is fully
* OpenGL-3.1-compliant.
* A smooth shaded polygon is drawn in a 2-D projection.
*/

/*
* Original copyright notice from smooth.c:
*
* License Applicability. Except to the extent portions of this file are
* made subject to an alternative license as permitted in the SGI Free
* Software License B, Version 1.1 (the "License"), the contents of this
* file are subject only to the provisions of the License. You may not use
* this file except in compliance with the License. You may obtain a copy
* of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
* Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
*
* http://oss.sgi.com/projects/FreeB
*
* Note that, as provided in the License, the Software is distributed on an
* "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
* DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
* CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
* PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
*
* Original Code. The Original Code is: OpenGL Sample Implementation,
* Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
* Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
* Copyright in any portions created by third parties is as indicated
* elsewhere herein. All Rights Reserved.
*
* Additional Notice Provisions: The application programming interfaces
* established by SGI in conjunction with the Original Code are The
* OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
* April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
* 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
* Window System(R) (Version 1.3), released October 19, 1998. This software
* was created using the OpenGL(R) version 1.2.1 Sample Implementation
* published by SGI, but has not been independently verified as being
* compliant with the OpenGL(R) version 1.2.1 Specification.
*
*/